1. Field of the Invention
This invention relates to a flexible mounting for an end-supported stator core in a dynamoelectric machine, and more particularly to a structure employing end boxes for the entire mounting and support of a stator core in a horizontal direction and for attenuating radial vibrations of the stator core.
2. Description of the Prior Art
The practice of attenuating radial vibrations of a stator core is known in the art and is typically accomplished by employing either vertically-flexible springs or horizontally-flexible springs between the stator core and an adjacent dynamoelectric machine frame along the entire length of the stator core. According to other known practices, an end-supported mounting for a stator core is achieved through the use of one or two bore rings for a stator core of a dynamoelectric machine of a relatively low rating. When more than one pair of bore rings is required as, for example, in a relatively long dynamoelectric machine, the intermediate bore rings are connected to an outer frame which extends along the complete length of the stator core. In these known constructions, the practices of attenuating radial vibrations of a stator core demand the use of a radially-outward adjacent structure to support the core radially along the complete axial length of the core. Such support is necessary to allow all sections of the stator core to circumferentially rotate the same distance during a short-circuit condition. These support arrangements eliminate slippage between punchings and subsequent stator core and coil insulation damage for machines of relatively large rating. However, these known arrangements are not economical for dynamoelectric machines of moderate power ratings such as air-cooled medium turbine generators.
A commonly assigned copending patent application by J. M. Mayher and A. S. Ying Ser. No. 965,007 filed Nov. 30, 1978, illustrates multiple springs disposed on both sides of a supported stator core with those springs being joined to selected bore rings encircling that stator core. The illustrated stabilizer constituted a single spring (25) which was joined to the bore rings below the stator core and prevented substantial horizontal movement of the stator core. While such structure uniformalized the circumferential displacement of the stator core at the bore rings' axial locations over previous support structures, it was subsequently determined from extensive analysis that under some operating conditions non-uniform circumferential displacement of the stator core could be obtained with such structure.